Drive Belt Snapped -- Cause?

[Luigi]

Hey gang. My alternator drive belt broke this morning, thankfully just a few blocks from home while I was on my way to work. I was able to drive back home with no power steering, just on battery power, and before my car was fully warmed up and caring that the water pump was no longer turning!

So, when I replaced the water pump a year ago, I also replaced the idler pulley and belt tensioner pulley. Aside from "simply" it being a defective drive belt, can you think why else my drive belt would snap? I don't want to put a new one on only to have the same problem again down the road -- need to fix a cause, if there is one. Thanks.

[TRELO]

Remove the broken belt and turn the pulleys by hand. Seen a few e46s w locked up
Alternators. Could be a defective pulley you put or simply the belt.

Check for grinding or binding. Could be that wp too


Opa iPhone

[spencers]

Remove the broken belt and turn the pulleys by hand. Seen a few e46s w locked up
Alternators. Could be a defective pulley you put or simply the belt.

Exactly. Check those pulleys as well. Where were the pulleys purchased from?

Was the belt the same size as OEM?

[Luigi]

Nice, thanks TRELO -- I gave each the pulleys a cursory quick spin after I pulled the belt out and all spun fine -- didn't detect binding or grinding. Will check better once I'm home, though. But the locked up alternator -- come to think of it, I'm not sure I tried to turn its pulley. OK, got some troubleshooting work ahead of me. Power sterering pulley, water pump pulley, alternator pulley, idler pulley and belt tensioner pulley -- that's it, right? Ah, I hate this crap sometimes. Dang it all. Again, thanks for the help.

[Luigi]

Spencers, thanks much. Pulleys and belt from my local parts store -- not OEM. I held the old belt up against the new one to make sure it was the same length. Do you strongly recommend OEM belt? Not ready to deal with the pulleys again, quite yet.

[spencers]

I think if the replacement belt is within the OEM size by a couple millimeters, you should be fine. Personally, I like Gatorback belts.

Aside from spinning the pulleys, you also want to check for pulley wobble.. Try to wiggle it about its axis and look for play.

[Luigi]

All good stuff -- thanks much for taking the time to share your advice. I'll be trying all you recommend. Time to get the coveralls out and work gloves on.

The car was whisper quiet this morning, too. No squeaks or squeals ... hmmm. Just sudden battery light on, power steering bye, bye, and you know the rest.

[aurelius]

Power sterering pulley, water pump pulley, alternator pulley, idler pulley and belt tensioner pulley -- that's it, right?

There is also a pulley on the alternator. Haven't heard it's problematic but it is replaceable. How many miles on your car?

[danewilson77]

Search e46 pulleys on youtube and there will be a video showing you what to look for when inspecting your pulleys.

The pulleys should not spin freely, and should have some resistence...in a nutshell.

Droid + Tapatalk = FTW!

[Luigi]

Guys, thanks again for the additional replies and help! So appreciated. It's got 69,000 miles. Youtube, I'm there -- thanks!

This is weird because I've been working on cars since I could drive, but somehow I've escaped pulley and belt troubles until now! That's very strange to me ...

[aurelius]

The current bmpdesign.com (BMW
& Mini catalog) email newsletter has a good primer on belts & pulleys, with links to videos.

[danewilson77]

Guys, thanks again for the additional replies and help! So appreciated. It's got 69,000 miles. Youtube, I'm there -- thanks!

This is weird because I've been working on cars since I could drive, but somehow I've escaped pulley and belt troubles until now! That's very strange to me ...

I bet you escaped FSR and CPS issues as well.

Droid + Tapatalk = FTW!

[Luigi]

If only I knew what FSR and CPS stood for! Guys, I'm so lame for being so slow to get back with the resolution on this. I researched like heck and watched a few YouTube videos, per your recommendations. But after all that good stuff I can only conclude that I had a cheap, defective belt (after market). The pulleys were all in good shape and spinning freely. And there was no sign of belt residue, burning, what have you, on any of the pulleys from the belt dragging across a tight pulley. Anyway, all these weeks later the nicer Continental drive belt I installed seemed to do the trick. No problems whatsoever now. I know, sounds too good to be true, and yet ...

I've been buried professionally and personally, so haven't been here for well over a month. The reunion looked epic. What a terrific event and great group of guys and gals. Good times! (Still viewing all the pictures ...)

[Hornung418]

The pulleys are not supposed to spin freely!!! They should spin maybe 1-2 revolutions and then stop immediately.

[danewilson77]

FSR.....final stage resistor.

CAB....control arm bushing.

HTC Thunderbolt+TT

[Luigi]

Oh, I did a poor job describing the action of the pulleys -- it's as you described them. Sorry for being unclear. They are acting as good, recently replaced by me pulleys should! (I replaced the idler pulley and the belt tensioner pulley when I replaced the water pump.)

And believe it or not, I replaced the final stage resistor preventatively (didn't recognize the acronym FSR). Not really a job for guys over 6 feet tall, I'd like to say. Isn't it fun laying on your back, with your legs on the passenger seat and up and over the back of the reclined seat back? Weeee!!!! And at around 52K, the driver's side control arm bushing was shot, so I replaced it and the passenger side. That was only a moderately unpleasant job. So, yes, I'm having my fair share of maintanence and repair fun -- I promise! Guys, thanks for the replies. Greatly appreciated.